Percussive tool.



W. CLEMENT.

PERGUSSIVE TOOL. APPLICATION FILED MAY 31, 1912. RENEWED MAY10,1913.

WITNESSES.

iw. 4 42M Patented Nov. 11, 1913.

UNITED STATES PATENT OFFICE.

WILLIAM CLEMENT, OF PHILLIPSIBURG, NEW JERSEY, ASSIGNOR T0 INGERSOLL-RAND COMPANY, OF NEW YORK, N. Y.', A CORPORATION OF NEW JERSEY.

PERCUSSIVE TOOL.

Application filed May 31, 1912, Serial No. 700,621.

Specification of Letters Iatent.

To all whom it may concern Be it known that I, \VILLIAM CLEMENT, a citizen of the United States, residing in Phillipsburg, in the county of Warren and State of New Jersey, have invented certain new and useful Improvements in Valves for Percussive Tools, of which the following is a specification.

This invent-ion relates to valves for percussive tools and more particularly to valves for that type of tool which is provided with inlet passages at the extreme ends of the cylinder and exhaust passages from points in the cylinder at a distance from the ends of the tool, the valve being thrown by compression produced by the movement of the piston, after it has overrun the exhaust ports, which is exerted against the surfaces of the valve through the inlet passages. In these valves as heretofore constructed the pressure tending to hold the valve in thrown position has been considerably greater than the opposed pressure and it has been necessary in order to overcome this excess to obtain considerable compression in the ends of the cylinder to throw the valve.

The object of the presentinvention is to produce a valve of this type wherein opposing pressures will be practicall balanced before the piston overruns the ex aust ports so that a very slight degree of compression will throw the valve, rendering its action quicker and more positive. With this object in view I have devised a valve a practical embodiment of which is shown in the to the rearward fluid pressure in the port Figure 1 is a longitudinal section of the tool taken on the line I-I of Fig. 2. Fig. 2 is a similar section at right angles to Fig. 1, taken on the line II,II'of Fig. 1 and Fig. 3 is a sectional view of a modified form I accompanying drawings in which:

of the valve spool.

The tool as shown comprises a cylinder 1 in which reciprocates a piston 2 which actuates by its impact the chipping chisel or other tool-piece 3. To the other end of the tool is secured the handle 4=which is threaded on the backend of the cylinder and holds f be of the same diameter throughout its length, from which projects a flange 7. From the inlet of the tool a passage 8 leads to what may be termed the inlet chamber,

or space, in the valve chest, which comprises chambers 9 and 10, at the ends of the valve,

RElSSUED passage 14, and port 13 leading directly into the back end of the cylinder. These ports are so constructed as to be closed alternately by the end faces of the valve body 6. Between the chambers 9 and 10 and surrounding the valve body is the exhaust chamber 15 which communicates with the atmosphere through the passage 16. In the opposite faces of the valve chamber 15 are annular exhaust ports 17 and 18 which are so placed as to be alternately closed by the opposite faces of the flange 7. From port 17 the passage 19 leads to the interior of. the cylinder opening into it at a point some distance from the back end. From port 18 the passage 20 leads to the cylinder openin into it at a point a short distance from tie front end of the cylinder. The area of the ports 17 and 18 is an important feature of the present design. When port 17 isv closed by the rear face of the flange 7 the area of the flange 7 which is exposed to the forward pressure of the fluid in port 17, must be approximately equal to the area of the front end of the valve body 6 which is exposed at the same time to the fluid pressure in inlet chamber 10. In the same way the area of the forward face of the flange 7 exposed 18 must be approximately equal to the area faces are in each case a few per cent. largerthan the opposing pressure areas on the flange'faces, in order to prevent fluttering, but the essential idea of the present invention is that these opposed surfacesshall be of approximately equal area.

In'Fig. 3 is shown a modification of the valve spool, the distinction between this and the form shown in Figs. 1 and 2 being merely that the spool is hollowed out to make it as light as possible. In this modification the faces of the valve body are madeup of the edges of the hollow valve cylinder together with the surfaces -o f the 1 hold it-in rearward position.

- back surface of the valve the port 17 which is closed atthat time by inner end of the bore in each end of the valve body, the operation of this valve being the same'in practice and theory as the solid spool. p

In operation, supposing the parts to be in the position shown in Fig. 2, fluid under pressure will be introduced into the back end of the cylinder through the passages 8 and 11, chamber. 10 and port 13, and will drive the piston forward. When the piston is in the position shown in the figure the forwardend face of the valve body 6 will be exposed to live fluid pressure tendlng to There will also be a pressure exerted in the same direction on account of the fluid from the front of'the cylinder exhausting through the passage 20 and streaming against the front face of the flange 7 as it passes through exhaust passage 16. As soon however as the piston uncovers the opening of the exhaust passage 19 live fluid pressure w1ll be exerted from the cylinder through passage 19 on the ange exposed to flange 7. As the area of this port and consequently the area of the flange exposed theretois approximately equal to the area of the forward end of the valve body the live fluid pressure on the valve will be practically balanced in both directions. As soon as the piston covers the end of the passage 20 the valve will be practically in equilibrium as there will be no further air escaping from the front end of-the cylinder through passage 20 and pressingbackwardly on the front faceof the valve flange. .It is evident therefore that the piston will have to overrun the passage 20 a very slight distance in order to produce suflici'ent compression in the front end of the cylinder to overbalance the valve and throw it forward, closing port 13 and admitting fluid to the front end of thecylinder through the port '12 and passage 14 to carry the piston in the other direction. In the same way, as the area of the flange 7 exposed t9 port 18 is approximately equal to the rear end face of the valve body, the live fluid pressures on the valve will be again balanced as soon as thepiston clears the end of the passage 20 on its backward stroke, enablin the valve to, be thrown rearwardly very s ortly after the piston covers passage 19. In is evidentthat by-throwing the valve more quickly in this way, a quicker and more powerful stroke of the piston will be secured.

By'the expressions inlet space and exhaust space as used in the claims are meant any series of passages or chambers which convey fluid to the cylinder inlet ports or take it from the exhaust ports, it being evident that-the tool might'be constructed so that live fluid .is introduced through the ports controlled by the flange and thuspasses throu h but a single chamber in reaching the inlet ports to both ends of the cylinder while the exhaust ports might be controlled by the end faces of the valve, the fluid thus passing through two separate chambers, without any invention being involved.

It is to be understood that the resent showing and descri tion discloses on y cering to points at a distance from the ends of the cylinder, said cylinder end ports arranged to be alternately opened and closed .by the ends of the valve and said flange chamber ports to be alternately opened and closed by the faces of the flange, the area of each of said flange faces exposed to pressure from the cylinder when covering its flange chamber port being approximately equivalent to the area of the opposed valve piston end, inlet passages leading to the valve cylinder ends and an exhaust passage'leading from saidexhaust chamber.

2. In a percussive tool, a cylinder, a valve chest havlng a bore and a chamber therearound, a valve having a body fitting said bore and reciprocating therein and a flange reciprocating in said chamber, exhaust passages from the cylinder controlled by the faces of said flange, and inlet passa es controlled by the ends of said valve bo y, said inlet passages also serving to convey compression from the cylinder to throw the valve.

3. In a percussive tool, a cylinder, a valve chest havlng a bore and a chamber therearound, a valve having a body fitting said bore and reciprocating therein and a flange reciprocating in said chamber, exhaust passages from the cylinder controlled by the faces of said flange, and inlet passages con-' the ends of the valve body and the faces of saidflange forming two sets of fluid passage controlling faces, inlet passages to said cylinder controlled by one of said sets of faces, and exhaust passages from said cylinder controlled by the other of said sets of faces, said inlet passages also serving to convey loo on said body reciprocating in said chamber,

the ends of the valve body and the faces of said flange forming two sets of fluid passage 10 controlhng faces, inlet passages to said cyl- 'inder controlled by one of said sets of faces,

and exhaust passages from said cylinder con-.

trolled by the other of said sets of faces.

6. In a'percussive tool, a-cylinder, a valve 15 chest having a bore and a chamber therearound, a valve having a body fitting said bore and reciprocating therein and a flange reciprocating in said chamber, exhaust passages from the cylinder controlled by the I faces of said flange, and inlet passages controlled .by the end faces of said valve body, said lnlet passages also serving to convey valve.

7. In a percussive tool, a cylinder, a valve chest having a bore and a chamber therearound, a valve having a body fitting said bore and reciprocating therein and a flange reciprocating in said chamber, exhaust passages from the cylinder controlled by the faces ofsaid flange, and inlet passages controlled by the endfaces of said valve body. v WILLIAM CLEMENT. Witnesses:

L. C. BAYLns, E. S. Arena.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of (Patents,

' Washington, I). G.

compression from thecylinder to throw the 

